Role of P-glycoprotein in deoxynivalenol-mediated in vitro toxicity

Deoxynivalenol (DON) is the most prevalent mycotoxin produced by grain-infecting Fusarium strains and frequently occurs in small cereals all over the world. After ingestion, DON is absorbed in the gut, which leads dose-dependently to critical health effects. In the present study, we have further investigated DON's previously reported affinity to the efflux transporter P-glycoprotein (Pgp) in the apical enterocyte membrane. Interaction with Pgp was studied in human colorectal adenocarcinoma (Caco-2) cells and Madin-Darby Canine Kidney wild-type (MDCKII-wt) and Pgp-overexpressing (MDCKII-MDR1) cells in different transport and cytotoxicity experiments. We found that DON was exported by Pgp and was less cytotoxic in Pgp-overexpressing cells. In the fluorometric calcein-acetoxymethylester (Calcein AM) assay DON reduced intracellular calcein retention, indicating a stimulation of Pgp-mediated efflux. In the presence of the selective Pgp inhibitors verapamil (Ver) and valspodar (PSC 833) the effect was, respectively, distinctive and significant. Verrucarol, a structural analogue of DON, was much less effective indicating the importance of the α, β-conjugated carbonyl group in the DON molecule for Pgp interaction. Our results confirmed that Pgp might have the potential to reduce intestinal absorption of DON in vivo. Furthermore, we were able to show that DON can modulate Pgp activity in vitro.